Jagiellonian University

About: Jagiellonian University is a education organization based out in Krakow, Poland. It is known for research contribution in the topics: Population & Catalysis. The organization has 17438 authors who have published 44092 publications receiving 862633 citations. The organization is also known as: Academia Cracoviensis & Akademia Krakowska.

Charged particle multiplicity near mid-rapidity in central Au + Au collisions at $S^{(1/2)}$ = 56-A/GeV and 130-A/GeV

Abstract: We present the first measurement of pseudorapidity densities of primary charged particles near midrapidity in Au+Au collisions at sqrt[s(NN)] = 56 and 130 GeV. For the most central collisions, we find the charged-particle pseudorapidity density to be dN/deta|(|eta|<1) = 408+/-12(stat)+/-30(syst) at 56 GeV and 555+/-12(stat)+/-35(syst) at 130 GeV, values that are higher than any previously observed in nuclear collisions. Compared to proton-antiproton collisions, our data show an increase in the pseudorapidity density per participant by more than 40% at the higher energy.

Virial masses of galactic haloes from galaxy–galaxy lensing: theoretical modelling and application to Sloan Digital Sky Survey data

Abstract: We present a theoretical analysis of galaxy–galaxy lensing in the context of halo models with cold dark matter motivated dark matter profiles. The model enables us to distinguish between the central galactic and non-central group/cluster contributions. We apply the model to the recent Sloan Digital Sky Survey (SDSS) measurements with known redshifts and luminosities of the lenses. This allows one to model accurately the mass distribution of a local galaxy population around and above L*. We find that the virial mass of an L* galaxy is M200= (5 − 10) × 1011h−1 M⊙ depending on the colour of the galaxy. This value varies significantly with galaxy morphology, with M* for late types being lower by a factor of 10 in u′, a factor of 7 in g′ and a factor of 2.5–3 in r′, i′ and z′ relative to early types. The fraction of non-central galaxies in groups and clusters is estimated to be below 10 per cent for late types and around 30 per cent for early types. Using the luminosity dependence of the signal, we find that for early types the virial halo mass M scales with luminosity as M∝L1.4±0.2 in red bands above L*. This shows that the virial mass-to-light ratio (M/L) is increasing with luminosity for galaxies above L*, as predicted by theoretical models. The virial mass-to-light ratio in the i′ band is 17 (45) h M⊙/L⊙ at L* for late (early) types. Combining this result with cosmological baryon fraction, one finds that 70 (25) per cent h−1ΥiΩm/12Ωb of baryons within r200 are converted to stars at L*, where Υi is the stellar mass-to-light ratio in the i′ band. This indicates that for both early- and late-type galaxies around L* a significant fraction of all the baryons in the halo is transformed into stars.

Reinforcement Learning with Unsupervised Auxiliary Tasks

Abstract: Deep reinforcement learning agents have achieved state-of-the-art results by directly maximising cumulative reward. However, environments contain a much wider variety of possible training signals. In this paper, we introduce an agent that also maximises many other pseudo-reward functions simultaneously by reinforcement learning. All of these tasks share a common representation that, like unsupervised learning, continues to develop in the absence of extrinsic rewards. We also introduce a novel mechanism for focusing this representation upon extrinsic rewards, so that learning can rapidly adapt to the most relevant aspects of the actual task. Our agent significantly outperforms the previous state-of-the-art on Atari, averaging 880\% expert human performance, and a challenging suite of first-person, three-dimensional \emph{Labyrinth} tasks leading to a mean speedup in learning of 10$\times$ and averaging 87\% expert human performance on Labyrinth.